The present disclosure relates to a paper feeding device and an image forming apparatus including the paper feeding device.
An image forming apparatus is provided with a paper feeding device for storing and feeding paper sheets to be used for printing. The paper feeding device is usually a type in which only one size of paper sheets can be set. However, when the paper feeding device that supports A3 size is used for setting A4 or B5 paper sheets, for example, there is a large vacant space. Accordingly, there is a case where a single paper feeding device is capable of setting sets of paper sheets in parallel so that more paper sheets can be stored.
There is known a sheet feeding device in which two sets of paper sheets can be set. Specifically, there is known a sheet feeding device capable of performing tandem feed operation, in which a first sheet loading table is movable up and down, a sheet is fed from the first sheet loading table, a second sheet loading table capable of moving up and down is disposed side by side with the first sheet loading table substantially in a horizontal direction, a set of sheets on the second sheet loading table is moved onto the first sheet loading table, when the set of sheets is moved, stop positions of the first sheet loading table and the second sheet loading table stopping at substantially the same height are detected, and when sheets on the first sheet loading table run out, the set of sheets on the second sheet loading table is automatically moved onto the first sheet loading table so that sheet feeding operation is continued.
In the known sheet feeding device described above, a spare set of sheets is moved onto the sheet loading table that has run out of sheets. In contrast, there is a paper feeding device in which a plurality of trays are disposed in a single-stage paper feeding device, and each tray can feed paper sheets (hereinafter, this paper feeding device is referred to as a “multi-tray housing paper feeding device”). In other words, in the multi-tray housing paper feeding device, one (stage) paper feeding device is divided into a plurality of rooms, and paper sheets can be fed from each room.
In the multi-tray housing paper feeding device, a plurality of (e.g., two) sets of relatively small size paper sheets can be set side by side. In the multi-tray housing paper feeding device, a paper feed roller and a tray elevation mechanism are disposed for each tray. Further, each tray is moved up so that each paper feed roller contacts with the paper sheet on each tray in accordance with remaining paper sheets on each tray.
The multi-tray housing paper feeding device has a merit that the space in the paper feeding device can be effectively used so that the number of paper sheets to be stored can be increased. On the other hand, in the multi-tray housing paper feeding device, a size of one paper sheet tray becomes small, and a large size of paper sheet (for example, a tabloid size or an A3 size) cannot be set. Conventionally, the multi-tray housing paper feeding device has a problem that large size paper sheets cannot be structurally set, and hence the usability is not good.
Here, the known paper feeding device described above can house two sets of sheets in a single stage of space. However, it is not expected to set large size paper sheets larger than the tray in the paper feeding device, and hence the above-mentioned problem cannot be solved.